People with chronic kidney disease are at unusually high risk of also developing cardiovascular disease; in fact, a patient with non-dialysis kidney disease is more likely to die of heart failure than to develop end-stage kidney failure. However traditional atherosclerosis risk factors contribute less strongly to cardiovascular disease in chronic kidney disease patients than in subjects with intact kidney function. Researchers are still trying to figure out how chronic kidney disease is linked to cardiovascular disease and how best to prevent it. In a recent study in the Journal of Lipid Research, Kathrin Untersteller and colleagues at Saarland University Medical Center in Germany and the Medical University of Graz in Austria undertook a detailed longitudinal study of patients with chronic kidney disease who were not on dialysis.
Altered kidney function is known to change the protein content of high-density lipoproteins, or HDL, which are inversely correlated with heart disease in the general population. Untersteller and colleagues hypothesized that that the level of HDL (known as "good cholesterol") or its protein makeup in a patient's serum at enrollment could predict the risk of cardiovascular disease in the next five years. Contrary to their expectation, after conducting the study the researchers concluded that, although some characteristics of HDL correlated weakly with future heart disease risk, no characteristic could be used independently to predict risk after controlling for other risk factors. The study underscores the complexity of untangling causality in clinical studies.